WASHINGTON – As President Donald Trump attacked House Democrats on Tuesday for launching various investigations against him, White House lawyers set up the prospect of a subpoena fight by rejecting a request for documents on security clearances.

The House committee seeking the documents "has failed to point to any authority establishing a legitimate legislative purpose" for its "unprecedented and extraordinarily intrusive demands," said a letter from White House Counsel Pat Cipollone.

Rep. Elijah Cummings, D-Md., chairman of the House Committee on Oversight and Reform, cited reports that Trump granted a top level security clearance to senior adviser and son-in-law Jared Kushner despite concerns raised by national security aides.

"There is a key difference between a president who exercises his authority under the Constitution and a president who overrules career experts and his top advisors to benefit his family members and then conceals his actions from the American people," Cummings said.

Cummings said he would consult with other committee member about "our next steps," which could include a subpoena.

The document battle, likely the first of many between White House aides and House Democrats, erupted as Trump criticized his political opponents by saying they are more interested in the 2020 presidential campaign than in helping the country.

"Instead of doing infrastructure, instead of doing health care … they want to play games," Trump told reporters after signing an executive order instituting a plan to reduce suicides by veterans.